VOC and NOx under & Claude, S. Reimann, C. Plass-Dülmer, F. Rohrer, Matthias Hill, R. Holla, D. Kubistin, S. Solberg & ACTRIS colleagues EBAS Acknowledgement: The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement n° 262254. 1

ACTRIS-VOC/NOx Activities ACTRIS - Aerosols, Clouds, and Trace gases Research Infrastructure Network NA3: Near-surface observations of aerosols, clouds and trace gases WMO/GAW-VOC/NOx activity EMEP-VOC/NOx activity CCL Data reporting Quality assurance Meas. Guidelines Trend determination WCC / QA-SAC ACTRIS-VOC/NOx Activities Integration/Harmonization Funding EUSAAR, EARLINET, CLOUDNET, EMEP and GAW TFMM 18.-20.5.2016 VOCs and NOx in ACTRIS, Anja Claude et al.

data quality objectives (DQO‘s) for NO & NO2 TFMM 18.-20.5.2016 VOCs and NOx in ACTRIS, Anja Claude et al.

data quality objectives (DQO‘s) for VOCs TFMM 18.-20.5.2016 VOCs and NOx in ACTRIS, Anja Claude et al.

NA3: Near-surface observations of aerosols, clouds and trace gases Objective To maintain and consolidate provision of high quality data for the variables addressed by ACTRIS in order to assure the quality and stability of the network composed of more than 40 ACTRIS labelled stations around Europe Aims for reactive gases: increase the amount and quality of delivered data by control exercises through inter-calibration campaigns side-by side intercomparison for NOx and OVOCs/terpenes Implementation of «target gases» (VOCs) implementation of quality assurance tools for data submission update of the measurement guidelines (also for WMO-GAW) TFMM 18.-20.5.2016 VOCs and NOx in ACTRIS, Anja Claude et al.

ACTRIS station requirements NOx and VOC Instruments, instrument set up, suitable inlet lines, filter systems, material, gases, calibration and quality assurances procedures should be designed as recommended in the measurement guidelines for NOx (ACTRIS Deliverable 4.10, 2014) and VOCs (ACTRIS Deliverable 4.9, 2014 ), respectively. This includes, that each site should:   regularly calibrate the instrument with a certified calibration gas  NPL regularly perform zero gas measurements  perform monthly measurements of target gases (VOC) and submit the target gas results to EBAS submit data including uncertainty and precision to EBAS following the protocol, deadlines and use the submission templates participate at the annual data quality workshop provide feedback to the open issues in the ACTRIS QC/QA process TFMM 18.-20.5.2016 VOCs and NOx in ACTRIS, Anja Claude et al.

second revision or approval VOC data flow Internal data checks using ACTRIS-2 tools provided by EMPA January - March March 31st April 30th 2nd half of May July 31st automated feedback @ NILU: data format checker and 1st consistency checks 1. Submission level 0 data including target and zero to NILU: Label ACTRIS_PRELIM ACTRIS QA with EMPA-tool by EMPA Consistency checks EMEP QA by S. Solberg Data meeting Feedback to stations: open issues in the issue tracker Re-submission to EBAS second revision or approval problems / questions have to be addressed by the data provider; this will be tracked until a decision maker (EMPA/DWD) closes the issue (successful). Publication of final data at EBAS: «ACTRIS» data TFMM 18.-20.5.2016 VOCs and NOx in ACTRIS, Anja Claude et al.

VOC (event) data reporting (1st submission by March 31, YY): ---> NEW TEMPLATES provided by NILU for NMHCs level 0 (with target gas/ calibration/zero gas measurements) and level 2 http://ebas-submit.nilu.no/SubmitData/AdvancedDataReporting/ Metadata + time stamp, VOC-i (nmol/mol), VOC-i_ac, VOC-i_pr, numflag_VOC-i taken from http://ebas-submit.nilu.no/SubmitData/AdvancedDataReporting/Level0/NMHCVOCOVOClevel0.aspx TFMM 18.-20.5.2016 VOCs and NOx in ACTRIS, Anja Claude et al.

1-pentene 2015 (Hohenpeissenberg) Different detection limit definitions in ACTRIS & EMEP! 1-pentene 2015 (Hohenpeissenberg) DL 1-pentene measured 1-pentene fixed DL TFMM 18.-20.5.2016 VOCs and NOx in ACTRIS, Anja Claude et al.

VOC QA/QC in ACTRIS with „EMPA tool“ (excel sheet) 3.Ratio plots vs previous years for inspection of outliers 4.Ratio plots vs master station Currently: manual checks done by the data provider and checked by EMPA visually automated checks to be developed 5. Step: Annual VOC/NOx QC-Meetings (~2 days) TFMM 18.-20.5.2016 VOCs and NOx in ACTRIS, Anja Claude et al.

red color: data rejected/outlier NILU consistency checks of new VOC data (colored) receieved through EBAS-submit compared to existing data in EBAS (grey) by S. Solberg rank sum test applied The boxes mark the 25- and 75- quantiles with the median given inside. The whiskers extend to the min and max values or to the 1.5 times P25 and P75 if there is data beyond this range. These outliers are identified with small circles. The right panel presents the data in histograms with the relative frequency given on the y-axis.   These plots are based on the full new and old data sets without any consideration of seasonal variations. The purpose is to look for systematic shifts in absolute levels. A Wilcoxon Rank Sum Test (also called a Mann-Whitney U test) is applied to evaluate this in a statistical manner. This test is based on ranks and not on the data values themselves and is thus less sensitive to peak outliers than e.g. Student T tests See e.g. https://en.wikipedia.org/wiki/Mann%E2%80%93Whitney_U_test The Wilcoxon RS-test tests the hypothesis: H0: The two sample sets come from the same population, in practice that they come from a population with equal median values against the alternative hypothesis: H1: The two sample sets come from populations with differing median values red color: data rejected/outlier blue: data ok grey: historical data TFMM 18.-20.5.2016 VOCs and NOx in ACTRIS, Anja Claude et al.

Target gas measurements monitor… …the reproducibility of the instrument, the uncertainty of the measurement (deviation from expected values),the quality of the calibration procedure on a monthly and long-term scale. TFMM 18.-20.5.2016 VOCs and NOx in ACTRIS, Anja Claude et al.

second revision or approval NOx data flow Level 0 data (different formats) 1. Submission to WCC-NOx cloud QA process currently under lead by WCC-NOx File format unification/Data processing/Consistency checks Feedback to stations: open issues in the issue tracker Re-submission of Level 0 data to WCC-NOx cloud Data meeting to discuss problems and progress (regular?) Conversion to EBAS file format by WCC-NOx second revision or approval problems / questions have to be addressed by the data provider; this will be tracked until a decision maker (WCC-NOx) closes the issue (successful). Publication of final data at EBAS: «ACTRIS» data TFMM 18.-20.5.2016 VOCs and NOx in ACTRIS, Anja Claude et al.

Molybdenum converters are not recommended! NOx Data Submission to EBAS NOx (continuous monitor, 1 hour data): final 1-hour averaged data (NO, NO2, NO2+, NOy in ppb), including uncertainty, reproducibility, variability (16- and 84-percentile) and data flagging (Level-2 data) AND Measurement Guideline NOx-CLD: required metadata: PMT temperature, reaction cell pressure, ambient ozone concentration +temperature +humidity useful metadata (CLD): integration time, PMT-voltage, chamber/instrument temperatures, …. @ EBAS: Different templates for photolytic and molybdenum converters! molybdenum converters convert not only NO2, but also other gaseous reactive nitrogen components into NO Molybdenum converters are not recommended! TFMM 18.-20.5.2016 VOCs and NOx in ACTRIS, Anja Claude et al.

NOx Correction F. Rohrer WCC-NOx 1) Dark reaction with ambient O3 in inlet line : NO+O3 (hn = 0) O3 measurements required 2) H2O quenching: NO2* + H2O → NO2 + H2O H2O measurements required (or alternatively adequate drying) Dark reaction depends on residence time in the inlet line,temperature, and pressure Example taken from station with a long inlet line  most servere effect. If possible short line with high diameter to reduce the pressure gradient. @30 ppb O3 5s entspricht 5% 3) Offset correction: nighttime data when O3 > 20 ppb TFMM 18.-20.5.2016 VOCs and NOx in ACTRIS, Anja Claude et al.

Effect of subtracting night time NO CLD1 CLD2 CLD3 [ppb] DWD Met. Observatorium Hohenpeißenberg, April 12 Holla Seite 16

Effect of subtracting night time NO CLD1 CLD2 CLD3  reduces portion of datapoints with no overlap at all from 44 % to 21.4% DWD Met. Observatorium Hohenpeißenberg, April 12 Holla Seite 17

Reduction of flags in ACTRIS! NOx Reduction of flags in ACTRIS! simplification Different detection limit definitions in ACTRIS & EMEP! http://ebas-submit.nilu.no/SubmitData/RegularAnnualDataReporting/NOsubxsubregular.aspx TFMM 18.-20.5.2016 VOCs and NOx in ACTRIS, Anja Claude et al.

5 years of ACTRIS/EMEP (GAW) data processed Open questions/on-going issues NOx: Molybdenum converters are not recommended! NOx_pc vs NOx_mc, NO2 Correction of dark reaction with O3 and H2O quenching VOC & NOx: Detection limit definition Correct use of submission templates and correct format of files and correct use of flag lists! Automatisation of QA/QC process Data workshop (2015 data) next week in Jülich NOx side-by-side intercomparison at HPB in October 2016  robert.holla@dwd.de VOC side-by-side intercomparison at HPB Summer 2017  anja.claude@dwd.de TFMM 18.-20.5.2016 VOCs and NOx in ACTRIS, Anja Claude et al.

….increase the number of sites! NO2 VOCs ACTRIS EMEP ACTRIS EMEP …and spread and follow the SOPs and QA/QC procedures! TFMM 18.-20.5.2016 VOCs and NOx in ACTRIS, Anja Claude et al.

Thanks for your attention Photo by Stefan Gilge TFMM 18.-20.5.2016 VOCs and NOx in ACTRIS, Anja Claude et al.